gNB-CU-UP Downlink Data Delivery Status for Inter-gNB Handover
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current wireless networks face challenges in efficiently managing mobility and resource allocation across different protocols and hardware limitations, leading to suboptimal performance and packet dropping during handovers in 5G and NR networks.
Innovation Solution
Implementing a method that coordinates the Control Plane and User Plane separation by performing E1 bearer context modification before F1 UE context modification, and using the Downlink Data Delivery Status message to notify the gNB-CU-UP to stop delivering downlink PDCP packets before the gNB-DU stops transmission, thereby preventing packet dropping and improving F1-U bandwidth utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If downlink data transmission is stopped abruptly during handover, then handover speed is improved, but packet dropping increases
Solution Approach 1:
The source gNB-CU-CP sends a stop delivery indication to the source gNB-CU-UP before the handover is executed, allowing the user plane to prepare and stop delivering downlink PDCP packets in advance. This preliminary action prevents packet dropping by ensuring the user plane is ready before the actual handover occurs.
Solution Approach 2:
The system implements feedback mechanisms where the source gNB-CU-CP notifies the source gNB-CU-UP about the upcoming handover through stop delivery indications. This feedback loop ensures coordinated action between control plane and user plane, allowing the user plane to adjust its behavior based on control plane decisions.
2Device complexity
If control plane and user plane operate independently during handover, then system modularity is improved, but coordination efficiency deteriorates
Solution Approach 1:
The source gNB-CU-CP acts as an intermediary that coordinates between the control plane procedures and user plane data delivery. It sends stop delivery indications to the source gNB-CU-UP and forwarding indications to the target gNB-CU-UP, ensuring synchronized operation between control plane and user plane despite their modular separation.
Solution Approach 2:
The patent extracts the coordination function from the distributed gNB entities and centralizes it in the gNB-CU-CP. This allows the control plane to take charge of coordinating handover actions between source and target gNBs, while the user plane entities (gNB-CU-UP) execute the data delivery instructions, maintaining modularity while improving coordination.
Data Source
AI summary
A Next Generation Node-B (gNB) and methods of communication are generally described herein. The gNB is configurable to operate as a source gNB. The gNB is configured with logical nodes including a gNB central unit (gNB-CU) and a gNB distributed unit (gNB-DU). The gNB-CU comprises a gNB-CU control plane (gNB-CU-CP) for control-plane functionality, and a gNB-CU user plane (gNB-CU-UP) for user-plane functionality. When a handover of a User Equipment (UE) from the source gNB to a target gNB is performed, the gNB transfers, from the gNB-DU to the gNB-CU-UP, a downlink data delivery status (DDDS) message to indicate that the gNB-CU-UP is to stop transfer, to the gNB-DU, of downlink data intended for the UE.